src/main/java/rx/internal/operators/OperatorTakeLastTimed.java
/**
* Copyright 2014 Netflix, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package rx.internal.operators;
import java.util.ArrayDeque;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import rx.*;
import rx.Observable.Operator;
import rx.functions.Func1;
/**
* Returns an Observable that emits the last <code>count</code> items emitted by the source Observable.
* <p>
* <img width="640" src="https://github.com/ReactiveX/RxJava/wiki/images/rx-operators/last.png" alt="">
*
* @param <T> the value type
*/
public final class OperatorTakeLastTimed<T> implements Operator<T, T> {
final long ageMillis;
final Scheduler scheduler;
final int count;
public OperatorTakeLastTimed(long time, TimeUnit unit, Scheduler scheduler) {
this.ageMillis = unit.toMillis(time);
this.scheduler = scheduler;
this.count = -1;
}
public OperatorTakeLastTimed(int count, long time, TimeUnit unit, Scheduler scheduler) {
if (count < 0) {
throw new IndexOutOfBoundsException("count could not be negative");
}
this.ageMillis = unit.toMillis(time);
this.scheduler = scheduler;
this.count = count;
}
@Override
public Subscriber<? super T> call(final Subscriber<? super T> subscriber) {
final TakeLastTimedSubscriber<T> parent = new TakeLastTimedSubscriber<T>(subscriber, count, ageMillis, scheduler);
subscriber.add(parent);
subscriber.setProducer(new Producer() {
@Override
public void request(long n) {
parent.requestMore(n);
}
});
return parent;
}
static final class TakeLastTimedSubscriber<T> extends Subscriber<T> implements Func1<Object, T> {
final Subscriber<? super T> actual;
final long ageMillis;
final Scheduler scheduler;
final int count;
final AtomicLong requested;
final ArrayDeque<Object> queue;
final ArrayDeque<Long> queueTimes;
public TakeLastTimedSubscriber(Subscriber<? super T> actual, int count, long ageMillis, Scheduler scheduler) {
this.actual = actual;
this.count = count;
this.ageMillis = ageMillis;
this.scheduler = scheduler;
this.requested = new AtomicLong();
this.queue = new ArrayDeque<Object>();
this.queueTimes = new ArrayDeque<Long>();
}
@Override
public void onNext(T t) {
if (count != 0) {
long now = scheduler.now();
if (queue.size() == count) {
queue.poll();
queueTimes.poll();
}
evictOld(now);
queue.offer(NotificationLite.next(t));
queueTimes.offer(now);
}
}
protected void evictOld(long now) {
long minTime = now - ageMillis;
for (;;) {
Long time = queueTimes.peek();
if (time == null || time >= minTime) {
break;
}
queue.poll();
queueTimes.poll();
}
}
@Override
public void onError(Throwable e) {
queue.clear();
queueTimes.clear();
actual.onError(e);
}
@Override
public void onCompleted() {
evictOld(scheduler.now());
queueTimes.clear();
BackpressureUtils.postCompleteDone(requested, queue, actual, this);
}
@Override
public T call(Object t) {
return NotificationLite.getValue(t);
}
void requestMore(long n) {
BackpressureUtils.postCompleteRequest(requested, n, queue, actual, this);
}
}
}